Fluidized Bed Gasifier Research Articles

Experimental investigation of hydrogen-intensified synthetic natural gas production via biomass gasification: a technical comparison of different production pathways

A sustainable and secure energy supply requires alternative concepts for energy generation. Utilizing biomass to produce synthetic natural gas (SNG) allows the synthesis of a currently widely used energy carrier on a renewable basis. The additional integration of hydrogen increases the carbon utilization of the biomass. This study experimentally investigates and compares the production of raw-SNG in three novel process chain configurations combining the advanced dual fluidized bed (DFB) gasification technology, gas cleaning units, and a fluidized bed methanation reactor. The three process chains comprise the direct methanation of DFB product gas, a hybrid route with hydrogen addition to the DFB product gas, and the methanation of a hydrogen-enriched product gas generated through DFB gasification with in situ CO2 removal (SER process). The direct methanation of the DFB product gas yielded a raw-SNG CH4 content of 40 vol.-%db at 360 °C and atmospheric pressure conditions. Through the integration of external hydrogen in a hybrid process, the carbon utilization of the biomass could be increased from 37% to around 70% at an unchanged cold gas efficiency of 58–59%. Via the SER process, a high raw-SNG CH4 content of 70 vol.-%db was achieved at an increased cold gas efficiency of 66% without the need for external hydrogen. Finally, a comparison points out the main advantages of the process configurations and provides a decision basis for novel SNG production pathways.

Investigation of Bubble Properties in a Bubbling Fluidized-Bed Gasification Reactor Using a Computational Particle Fluid Dynamic Model

Investigation of Bubble Properties in a Bubbling Fluidized-Bed Gasification Reactor Using a Computational Particle Fluid Dynamic Model

Experimental study on effect of temperature and equivalence ratio on biomass syngas generation for fluidized bed gasifier techniques

ABSTRACT This paper presents a comparative study of selected woody biomass for the potential of fuel gas generation that can be used for heat and power generation using a Fluidized Bed Gasifier (FBG). The characteristics of produced energy gas using the thermochemical Bubbling Fluidized Gasification Technique for selected woody biomass feedstock materials were studied for selected temperatures. Initially, the CFD analysis has been implemented to determine the feasible equivalence ratio (ER) for the selected biomasses. Using CFD ANSYS solver studied gas-solid interaction and gasification process inside a fluidized bed biomass gasifier. Experimental investigations were conducted on the FBG reactor for a feeding rate of 10 kg/hr of biomass materials. Experimental investigations were conducted on the FBG reactor for a feeding rate of 10 kg/hr of biomass materials. The work characteristics of produced gas were investigated by the experimental process for bagasse, groundnut shell, and wooden shavings as feedstock biomass materials for the gasification bed temperature at 500ºC, 550ºC, and 600ºC and Equivalence Ratio (ER) ratio of 0.30. Air was employed as a gasifying agent, and sand with limestone was used as the fluidized bed material. The results show that the fluidized bed has higher temperatures of 600ºC and above, generating higher Calorific Value (CV) syngas. Among all three feedstocks, groundnut shells produced gas HHV of 4.21 MJ/m3. The lowest HHV for bagasse at 500ºC of 3.01 MJ/m3. The effect of bed temperature on Carbon Conversion Efficiency (CCE) shows maximum CCE for bagasse is 60.86%, noted at 550ºC, and the minimum for wooden shaving at 550ºC is 57.69%.

Techno-Economic Analysis of Thermochemical Conversion of Waste Masks Generated in the EU during COVID-19 Pandemic into Energy Products

During the COVID-19 pandemic, more than 24 billion pieces of surgical mask waste (WM) were generated in the EU region, with an acute shortage of their management and recycling. Pyrolysis and gasification are among the most promising treatments that were proposed to dispose of WMs and convert them into pyrolysis oil and hydrogen-rich syngas. This work aimed to investigate the techno-economic analysis (TEA) of both treatments in order to assess the feasibility of scaling up. The TEA was carried out using a discounted cash flow model and its data were collected from practical experiments conducted using a fluidised bed pyrolysis reactor and bubbling fluidised bed gasifier system with a capacity of 0.2 kg/h and 1 kg/h, respectively, then upscaling to one tonne/h. The technological evaluation was made based on the optimal conditions that could produce the maximum amount of pyrolysis oil (42.3%) and hydrogen-rich syngas (89.7%). These treatments were also compared to the incineration of WMs as a commercial solution. The discounted payback, simple payback, net present value (NPV), production cost, and internal rate of return (IRR) were the main indicators used in the economic feasibility analysis. Sensitivity analysis was performed using SimLab software with the help of Monte Carlo simulations. The results showed that the production cost of the main variables was estimated at 45.4 EUR/t (gate fee), 71.7 EUR/MWh (electricity), 30.5 EUR/MWh (heat), 356 EUR/t (oil), 221 EUR/t (gaseous), 237 EUR/t (char), and 257 EUR/t (syngas). Meanwhile, the IRR results showed that gasification (12.51%) and incineration (7.56%) have better economic performance, while pyrolysis can produce less revenue (1.73%). Based on the TEA results, it is highly recommended to use the gasification process to treat WMs, yielding higher revenue.

Gasification of a bituminous coal in 15MWth KEDA®circulating fluidized-bed gasifier with high-temperature preheating

The industrial-scale high-temperature preheating air-blown KEDA®circulating fluidized-bed (KEDA®CFB) gasification process has been developed by KEDA(ANHUI) Clean Energy Co., Ltd. to produce industrial fuel gas. This paper presents the design and the first operational results of a 15MWth industrial-scale demonstration KEDA®CFB plant where about 3.6 tons bituminous coal was gasified per hour. The influences of the steam to coal ratio (SC), the equivalence ratio (ER), and the oxygen concentration (OC) on gas composition, gas high heating value (HHV), carbon conversion efficiency (CCE), and cold gas efficiency (CGE) were investigated systematically. It is shown that increasing SC from 0.18 to 0.38 favors the water–gas reaction and CO–shift reaction that causes H2 and CO2 content in the raw gas to rise. As ER increases to 0.27, it is conducive to the partial combustion and Boudouard reactions of char, and the HHV and CGE of gas products are 6.38 MJ/Nm3 and 66.8%, respectively. As OC increased from 21 vol% to 27 vol%, the CCE increased from 71.8% to 79.8% mainly due to the increase of gasification reaction rate and residence time. The operational results in this work can significantly contribute to the design and operation of industrial-scale gasifiers, and the development of numerical models.

Sewage sludge and digestate gasification in an atmospheric fluidized bed gasifier

The gasification of sewage sludge (SS) and digestate was investigated in a pilot-scale fluidized bed gasifier with an output of 100 kWt. The treatment of these by-products is an ongoing challenge for sustainable development. SS and digestate are most commonly used as fertilizers. However, regulations restrict their use, mainly because of the content of heavy metals, pathogens and bacteria. Gasification of these by-products instead of application to agricultural land seems to be more efficient, as the syngas can subsequently be used for combined heat and power (CHP) generation. A series of measurements were carried out to get a better understanding of the gasification process of these fuels and to study the effects of gasifying agent on the syngas composition, particulate matter (PM) and tar. The produced syngas and tar were analyzed using a gas chromatograph with mass spectrometry (GC–MS). The results showed that no ash slagging was observed and therefore it is feasible to operate digestate and SS gasification at 750°C. The lower heating value (LHV) of the syngas from digestate and SS with air as the gasifying agent is comparable, 4.06 MJ·Nm−3 for digestate and 4.11 MJ·Nm−3 for SS. The addition of steam had a positive effect on the amount of tar and the tar dew point, which was below 150°C. Tar reduction in digestate was 5037.3 mg·Nm−3 to 3566.3 mg·Nm−3 and in SS 7447.7 mg·Nm−3 to 3390.3 mg·Nm−3. Furthermore, the concentrations of the individual tar compounds were determined and subsequently divided into tar classes.

Numerical study of the biomass gasification process in an industrial-scale dual fluidized bed gasifier with 8MWth input

In the present numerical study, biomass steam gasification in industrial-scale dual fluidized bed gasifier with 8MWth input is numerically simulated via the multiphase particle-in-cell (MP-PIC) method, where the gas turbulence is controlled via large eddy simulation (LES), and the solid phase is tracked under the Lagrangian framework. This model has been well validated with experimental measurement. The gas and solid fluxes, gas distribution, gas and solid thermal properties together with the effect of solid inventory and steam-to-biomass ratio on the system performance are discussed in detail. Results show that the asymmetrical structure of the gasifier leads to a nonuniform distribution of gas phase. Product gases released in the gasifier have similar distributions. The vertical gas flux is much higher than those along radial directions, due to the fluidization characteristics. A decrease of the vertical gas temperature in the combustor and an increase of that in the gasifier are observed due to the improvement of solid circulation rate and heat transfer raised by increasing the solid inventory. Enlarging the solid inventory can increase the particle mean temperature at gasifier outlet while decreases that at gasifier inlet, and decrease the sand temperature and heat transfer coefficient along the combustor height. Moreover, the impact of inventory height and S/B on gas thermal properties in both reactors is discussed.

Effects of Jincheng coal fine char from fluidized-bed gasifier on ash fusion and CO2 gasification behaviors of biomass

Effects of Jincheng coal fine char from fluidized-bed gasifier on ash fusion and CO2 gasification behaviors of biomass

Performance evaluation of an innovative 100 kWth dual bubbling fluidized bed gasifier through two years of experimental tests: Results of the BLAZE project

In this work, the results of two years of experimental tests on an innovative dual bubbling fluidized bed gasifier are reported. These are related to the activities of the BLAZE project (Horizon 2020) for the integration of steam biomass gasification and solid oxide fuel cell. Several tests were carried out on the pilot-scale reactor at various operating conditions, and in this work the results are reported in terms of dry gas composition and yield, organic and inorganic contaminants (tar, particulate matter, H2S). The compact design of the gasifier (a single reactor with two concentric chambers and in-situ hot gas cleaning and conditioning) reduces the heat losses and produces close to nitrogen-free syngas. Preliminary tests using a filter candle filled with conventional catalyst, installed in the freeboard of the gasifier, show that the tar content dropped to about 2 g/Nm3, and the H2 concentration increased up to 41%vol,dry.

Fluidised bed gasification of biomasses and wastes to produce hydrogen‐rich syn‐gas – a review

AbstractThe sustainable fulfilment of world energy demand should be based on the diversification of the energetic portfolio and, at the same time, on the decrease of the use of fossil fuels in favour of renewable energy sources. This perspective review article focuses its attention on a particular source of renewable energy, i.e. biomass. As non‐fossil materials of natural origin, biomasses are formed by storing, in the noble and stable form of chemical bonds, solar energy. Gasification has been here chosen as biomass thermoconversion route: general concepts and history, chemical reactions and uses of syn‐gas, and the role of tar, are addressed. Fluidised beds are discussed as reactors to carry out biomass gasification, also considering that a new approach based on dual interconnected fluidised bed schemes can realise the concept of sorption‐enhanced gasification (to increase H2 productivity). Syn‐gas and tar characteristics are presented and, finally, an original case study concerning the fluidised bed gasification of civil and industrial sludges is presented. © 2023 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).

Hydrogen production and pollutants emission characteristics by co-gasified of paper-mill sludge and automobile shredder residues in a commercial scale fluidized bed gasifier

This research investigated the hydrogen production and energy conversion from automobile shredder residues (ASRs) and paper mill sludge (PMS) co-gasified in a full-scale fluidized bed gasification plant. The results obtained from full-scale tests provided important information on the feasible assessment of ASRs-to-energy and the selection of alternative technologies for ASRs. Based on the analysis results of produced gas composition, H2, CO, and CH4 composition produced from paper-mill sludge gasified were 4.17%–6.01%, 3.08%–4.32%, 1.71%–2.4%, respectively. Another C2 gas composition ranged from 2.9% to 3.59%. The heating value of produced gas ranged between 1.64 MJ/Nm3 and 2.18 MJ/Nm3. In the case of 10% ASR addition, the heating value of produced gas was slightly increased to 1.84 MJ/Nm3-2.34 MJ/Nm3. The dioxin emission concentration of flue gas was approximately 0.064 ng I-TEQ/Nm3. It can comply with Taiwan regulation thresholds. The dioxin leaching concentrations of residues derived from gasification were also in compliance with regulation limits by the TCLP test. Meanwhile, in the case of 10% ASRs addition, the dioxin equivalence concentration of gasified residue was nearly 0.002 ng I-TEQ/Nm3. It was far below the current regulation standard limit. In summary, the results of this research have proved the performance of ASRs-to-energy by co-gasified with paper mill sludge using a full-scale gasification plant. The results obtained from this research also provided the information for selecting ASRs alternative technologies and operating full-scale gasifiers in the future.

Experimental gas-fluidized bed drying study on the segregation and mixing dynamics for binary and ternary solids

Fluidized bed drying is an evolving process: The bed hydrodynamics, including the segregation and mixing tendencies, and its interplay with mass and heat transfer change in time. In this study, pseudo-2D fluidized bed experiments are performed using binary (50/50%) and ternary (33.3/33.3/33.3%) solids mixtures. A coupled particle image velocimetry infrared thermography technique provides local solids velocity and temperature fields. Furthermore, a machine learning algorithm is applied to characterize the bed segregation and mixing dynamics. Significant hydrodynamic changes and various segregation and mixing tendencies due to the evaporation of water from the porous γ-Al2O3 material were observed. A competition between size and density-based segregation and mixing dynamics resulted in changing bed configurations, which are correlated to the local solids drying behavior. Besides, it showed that drying of wider size distributions could lead to more complex efficient process operation.

Investigations on biomass gasification of compact-fast dual fluidized bed calcium looping

In this study, a 10 kWth hot rig of dual fluidized bed is developed to investigate the performance of the calcium looping process for biomass hydrogen-rich gasification and carbon dioxide capture. The system consists of a compact fluidized bed and a fast fluidized bed riser. The compact fluidized bed, which is comprised of a lower bubbling fluidized bed and an upper riser, is used as the gasifier, and the fast fluidized bed riser is used as the regenerator. The solid from the regenerator goes upward from the bottom of the upper riser gasifier, and then downward to the lower bubble fluidized bed gasifier, bringing heat from the generator to the gasifier, and is finally circulated to the regenerator form the bottom of the bubble fluidized bed, taking carbon dioxide from the gasifier to the regenerator. Dolomite and quartz sand are used as bed materials. The effects of variables such as temperature, bed material, and solid circulating flux on product gas compositions, yield, calorific value, tar content, and cold gas efficiency were investigated. The dolomite bed material has a more obvious improvement in hydrogen production as compared with quartz sand as bed material. The maximum H2 production is 0.46 Nm3/kgFuel, the purity reaches 70.88%, the cold gas efficiency is 45.93%, and the low calorific value is 13.26 MJ/Nm3. The high temperature of the upper riser favors tar conversion. When the riser temperature was 800 °C, the tar content decreased by 4.46 g/Nm3, and the total gas production increased by 0.03 Nm3/kgFuel. In addition, the increase of solid circulating flux can improve the concentration and the yield of hydrogen, and decrease the content of tar.

Chemical Kinetic Modeling of Air-Steam Gasification of Eucalyptus Wood Sawdust for H2-Rich Syngas Production.

The aim of this research paper is to develop a chemical kinetic model, based on the mechanism of surface reactions, for air-steam gasification of eucalyptus wood sawdust (CH1.63O1.02) and analyze the hydrogen-rich syngas production. Experiments are performed on a bubbling fluidized-bed gasifier using air-steam as a gasifying agent. For validation of the developed kinetic model, the outcome of the model is compared with that of experimental data, which shows a root-mean-square error of less than 4. Different parameters such as equivalence ratios (0 ≤ ER ≤ 0.4), particle size (100 ≤ Dp ≤ 1000 μm), gasification temperature (900 ≤ T ≤ 1200 K), pressure (1 ≤ P ≤ 20 atm), and steam-to-biomass ratio (0 ≤ SBR ≤ 2) are considered for the analysis. The one-parameter-at-a-time concept is employed to maximize the production of H2-rich syngas. Results indicate that the maximum concentration of hydrogen is 55.04 vol % (experimental) and 51.81 vol % (predicted) at optimum conditions: ER = 0, Dp = 100 μm, T = 1100 K, P = 1 atm, and SBR = 0.75. Gasification performance parameters such as hydrogen gas yield, heating values, cold gas efficiency, etc., are evaluated.

Thermal decomposition mechanism analysis of circulating solids sampled from Ende pulverized‐coal gasifier

AbstractEnde pulverized‐coal gasifier (EPCG) is a type of circulating fluidized bed gasifier, in which the circulating solids are resent into the furnace through a return conduit for regasification. Since the solid circulation in the return conduit mainly relies on gravity self‐balancing, it is easy to cause low and unstable solid circulation rate and increase unburned combustible of fly ash. To solve these problems, a circulation enhancement technique using an ejector to provide a stable pressure barrier to promote solid circulation was proposed. To verify its feasibility, considering that the circulating solid‐CO2 reaction is a rate‐controlling step in the gasification process, it is of great significance to explore the reactivity characteristics of the circulating solids under CO2 atmosphere. In this work, thermal decomposition characteristics of Hailar circulating solids (HLE‐CS), Hailar char (HLE‐C), and Shenhua circulating solids (SH‐CS) were investigated by non‐isothermal thermogravimetric analysis to compare the gasification reaction characteristics of circulating solids and char. The HLE‐CS and SH‐CS used in the experiments were taken from the return conduit of 45,000 and 20,000 Nm3/h EPCGs, respectively, while HLE‐C was made from the raw coal of 45,000 Nm3/h EPCG. The effects of different samples under the same thermal decomposition temperature range were investigated. The kinetic parameters were determined by the distributed activation energy model. The results indicated that remarkable peaks were found in the relationship between temperature (T) and activation energy (E) for HLE‐CS and SH‐CS, but there was no significant peak for HLE‐C, and kinetic compensation effects also existed between ln(k0) and E for different samples. The circulating solids of HLE‐CS and SH‐CS were more easily gasified than that of HLE‐C in the lower temperature ambience. Moreover, HLE‐CS and SH‐CS have obvious pyrolysis and gasification stages, which can be completely introduced into EPCG for regasification, and increasing the circulating solid rate and temperature within a certain range is beneficial to enhance the gasification rate.

Kinetics of H2S removal using alkaline residue as in-bed sorbent in fluidized bed gasification of biomass and wastes

The use of alkaline residue from the acetylene industry (carbide slag, CS) as in-bed sorbent to remove H2S from syngas from biomass/waste fluidized bed (FB) gasification was investigated. Measurements were conducted in a laboratory FB applying differential conversion technique, tracking the reaction using both gas measurements and solid analysis. Apparent reaction kinetics was obtained, without external mass transfer limitations, for different gas mixtures containing CO2, H2O, CO, H2 and CH4, having relatively low H2S concentration (500–1000 ppm). The addition of CO2 and H2O to an N2-H2-H2S mixture showed that the reaction rate was reduced in the presence of these species. Varying the H2 concentration between 7 and 14% in simple (N2-H2-H2S) reactive gas mixtures did not affect the results, while both CO and H2 potentially affected the reaction rate if also CO2 was present in the gas. Other operating parameters, such as sorbent particle size, sulfidation- and calcination temperature also affected the CaO sulfidation rate, which increased with temperature between 800 and 900 °C and was enhanced by higher calcination temperature. Specific surface area and pore size distribution of the calcined CS was measured before and after the sulfidation reaction, showing that CS maintained a large fraction of its original pore volume even after most of the CaO had been converted into CaS. The sulfidation rate of calcined limestone was also measured for comparison showing that the reaction rate using CS was slightly lower, but similar to that using limestone, showing that CS is a promising alternative to conventional calcium-based sorbents for high temperature H2S removal, contributing to promote the circular economy, while avoiding the current stacking of CS at the acetylene production sites.

The techno-economic-environmental analysis of a pilot-scale positive pressure biomass gasification coupled with coal-fired power generation system

Biomass gasification coupled with coal-fired power generation (BGCPG) is of great significance for alleviating energy shortages and environmental pollution. Here we propose, analyze and validate a BGCPG system under positive pressure for cleaner applications based on a pilot-scale fluidized bed gasification plant and discussed the possibility of higher economic output and operating stability with reduced pollution emissions. Then the effects of temperature, air equivalence ratio and operating pressure were experimentally investigated for parameter optimization. The processes under positive and negative pressure were simulated and compared based on the pilot-scale experimental data, and the effects of the mixing ratio and operating pressure were investigated. Furthermore, the economic and sensitivity analyses were conducted for both a traditional coal-fired power plant and simulated BGCPG systems. The results demonstrated that the gas calorific value, gas yield, and gasification efficiency increased with the gasification temperature increasing, whereas the opposite trend was observed for the gas calorific value with the air equivalence ratio increasing. The positive pressure operation had little influence on the gasification process. The flue gas flow rate increased, and the furnace temperature decreased with an increase in the mixing ratio of biomass and coal. The reduction in fuel NOx and SOx was caused by the decreasing coal content, whereas the decrease in thermal NOx and boiler thermal efficiency was due to the increasing exhaust temperature. Compared with functioning under negative pressure, operation under positive pressure at a 20% mixing ratio could effectively reduce the pollutant emissions of SOx, NOx and dust by 5.64%, 8.8% and 20%, respectively. The generation costs of the BGCPG system under negative and positive pressure conditions were 0.05593 $/kW·h and 0.05582 $/kW·h respectively, indicating that a positive operating pressure would increase the economic benefit of a 660 MW generator by 5.808 × 105 $/year. These findings suggest the effectiveness of clean power generation with a higher economy and lower pollution emissions.

Experimental evaluation of wood and grass pellets in a bubbling fluidized bed gasifier

Biomass gasification is an attractive technology capable of producing a versatile product gas that can be used for heat and power production as well as used as a feedstock for biofuels and higher-value chemicals synthesis. A fluidized bed gasifier is one of the better choices for an industrial scale operation. However, the specification and performance of different feedstocks must be characterized to use in a specific application with acceptable efficiency. In this article, the authors took two different feedstocks (i.e., wood and grass pellets) for the experimental characterization in a 20-kW pilot-scale bubbling fluidized bed gasifier. Equivalence ratio was varied between 0.1 to 0.2 for the grass pellets and 0.214 to 0.371 for the wood pellets. Frequent agglomerations were observed during the experiment with the grass pellets at a temperature of 800 °C and above. The carbon conversion for the gasification of grass pellets was observed to be lower compared to the gasification of wood pellets. Gasification of wood pellets gave a carbon conversion of around 60% at a temperature of around 850 °C.

Fluidized bed gasification of solid recovered fuels in a 500 kWth pilot plant

On the way to climate-neutrality with low resource consumption, the economics worldwide needs ways to obtain high-quality products from existing material flows. If waste is used as a feedstock for gasification, high-quality syngas is obtained from which new products for the chemical industry (e.g. methanol) or the transport sector (Fischer-Tropsch products) can be obtained. The fluidized bed-based High-Temperature-Winkler process is particularly suitable for the gasification of solid recovered fuel (SRF) and biomass that are difficult to grind since the feedstock can be processed in lump form. The gasification characteristics of SRF pellets were investigated in a 500 kWth pilot gasifier at the Technical University of Darmstadt. After a co-gasification with pre-dried lignite, a mono SRF gasification could be realized. This paper presents the effects of operating temperature and the SRF content in the feedstock on the syngas quality, which is characterized by the target components CO and H2, the undesired fraction of CH4, and some representative higher hydrocarbons. It could be shown, that the syngas gas components CO and H2 depend mainly on the gasification temperature and not on the used feedstock. On the other hand, the higher amount of volatiles in the SRF fraction rises the methane concentration and the amount of higher hydrocarbons in the syngas. It was observed that these components are decomposed at higher gasification temperatures and an almost tar-free syngas is produced.

Air and Air-Steam Gasification of Coconut Shell in a Fluidized Bed

Coconut shells’ abundance in tropical countries, along with its high volatile combustible matter (83.51%) and energy content (18.68 MJ kg-1) make it a good biomass resource and a promising feedstock for gasification. In gasification, different mediums such as air, steam, oxygen, or their combinations can be used to react with the solid carbon and heavy hydrocarbons of biomass. Hence, the effects of using an air-steam mixture as a gasifying agent for the bench-scale fluidized bed gasification of coconut shells were studied. The steam-to-carbon ratio (SCR) was varied to evaluate its effect on the resulting syngas quality and gasification performance, while the equivalence ratio was maintained at 0.25 and the bed temperature was kept at 700°C. Results revealed that the optimum SCR is 0.6, where peak values of hydrogen (H2) and methane (CH4) content, hydrogen-to-carbon monoxide ratio (H2/CO), higher heating value (HHV), cold gas efficiency (CGE), and carbon conversion efficiency (CCE) were observed. Furthermore, the use of the air-steam mixture (SCR 0.6) as a gasifying agent was compared with the conventional air gasification. The study also showed a significant increase in syngas quality in terms of H2 content (4.70 - 5.82%), H2/CO (0.30 - 0.39), and CH4 content (3.53 - 4.38%). The syngas heating value and gasification performance revealed a statistically similar improvement: HHV from 4.95 to 5.41 MJ Nm-3, CCE from 77.64 to 81.75%, and CGE from 47.99 to 51.01%. Moreover, air-steam gasification produced less CO2 (13.42 CO2mol kgbiomass-1) and had higher energy recovery (49.67%).